Process of and apparatus for separating desired liquefiable constituents from alpha gaseous mixture



June 2, 1931. E. H. LESLIE ET AL 1,808,420 PROCESS oF AND APPARATUS FOR SEPARATING DESIRED LIQUEFIABLE CONSTITUENTS FROM A GASEOUS MIXTURE Filed NOV. 22, 1924 kb@ www XQQ Patented June 2, 1931 UNITED STATES PATENT ol-Flfclaz4 EUGENE H. LESLIE AND' EDWIN M. BAKER, OIF AN N ARBOR, MICHIGAN PROCESS OF AND APPARATUS FOR SEPARATING DESIRED LIQUEFIAIBIE CONSTITUEN'IS FROM.' A GASL'OUS MIXTURE t Application led November 22, 1924. Serial No. 751,572.

This invention relates to processes of and apparatus for separating desired liquefiable constituents from a gaseous mixture; and in particular it relates to the production of 5 valuable normally liquid hydrocarbon mixtures of the motor fuel type, such as gasoline, from a mixture of hydrocarbon gases, such as natural gas; the procedure being characterized by compression of the hydrocarbon gas mixture to assist in liquefying the constituents which it is desired to recover, and.

by utilizing the heat of compression to effect al refining treatment of the resultant liquid products. A principal object of the invention is to provide a process and apparatus for more completely and eficiently carrying out operations of the typev generally described above; and in particular for more completely and efficiently recovering a stable and directly marketable gasoline from natural gas. While the invention is not limited to the treatment of natural gas for production of gasoline, that is its most useful field of application at the present time and-such application will therefore be referred to more particularly hereinafter in explaining the principles upon which the invention is based.

Briefly described, the present invention, as applied to the manufacture of gasoline from natural gas, comprises subjecting natural gas to compression in one or more stages, cooling thel compressed gases to obtain a condensate, and refining this condensate `by suitable heat treatment, in which the heat of the compression is utilized to eliminate from the crude condensate to the necessary extent the so-called Wild7 gases; the refining operation most desirably comprising a rectification of the crude condensate with the aid of a distilling column in such manner that the wild gases are eliminated either wholly or to any desired extent without substantial loss of those hydrocarbons which it is desired shall constitute the motor fuel or gasoline sought as the final product.

In order to explain further the principles of the invention, one practical way in which 5 it may be carried into effect will now be de Aitv is a horizontal tubular heater in which the scribed in detail in connection with an apparatus system which is especially well suited Y for carrying out the process and which is itself also novel. Said apparatussystemis illustrated more 'or less schematically linthef55 accompanying drawing which represents said system in elevation. L l In practicing the novelprocess by means of the apparatusfhere illustrated,-and assuming that the'production of gasoline fromco natural gas is involved, the naturalgas enters the'syst'em through the'pipe 10, passes through a sediment and watertrap- 11 and goes to the firstvstage compressor 12, where itis compressed to around 10V to 50 pounds, for example. kAs a result ofthe work done upon the gas in this compressor, the temperature is increased Vto stay 200 yto 250 F. The hot compressed gas leaving the first stage compressor passes through trap 1370 where some lubricating oil collects and thence through line 14 to a still or heater indicated generally at 15. As will appear more fully hereinafter, this heater cooperates with a distilling column for rectification of the crude condensate resulting from compression and cooling of the natural gas. Said heater may be of any 'suitable'type for thatl purpose, but in the installation here illustrated,

heating tubes 16, through' which the 'hot compression gases pass,.occupy only the lower half of the tube sheets, thus leavingA the upper half. of the vaporizing chamber as a free vapor space. This allows effective v aporization without tooV much entrainment of the liquid.

In passing through the heatingvtubes 16, some condensation of the heavier hydrocarbons occurs, such condensate passingV offl through pipe 17, while the gasesv pass off through pipe 18 and enter condenser 19 of any usual or suitable type. The vcondensate here obtained, together with residual gas and uncondensedl vapors, passes'from the condenser into the trap 20, the liquid flowing loff through pipe 21 which joins pipe 17, and

the combined cond-ensates then going through pipe 22 to a pump 23 which will be referred to again presently. The gas and the vapor 19 leaving trap 2() go by way of pipe 24 to the second stage compressor 25 where they are compressor to around 200 to 250 pounds. The hot compressed vapors areled through lubricating oil trap 26 and pipe 27 to a second tubular stiller heater 28 vwhich may be similartoheater Vl5. 'In this heaterfthe conipressed gases which may have attaineda temperature of 200 .130.2500 Ein the compressor give up heat to the liquid inthe heater, and

...a result-seme of .-the higher boiling constituents of the compressed gas are condensed and flow through pipe 29 to pump 30. The

gases and uncondensed vapors leave `the heater through pipe 31 and pass to condenser 32. 'The ycondensate here obtained and separated tromjthe' residual gases in trapf32av vgoes throuzgh pipe 133 to .thel pump 30, the pipes '-29 and-33 merging into a common pipe 34 enteringl `said pump. Said residual gases leaving the condenser 32pass through pipe 35 to a rectifyinglcelumn. IThis vcolumn is ahere. shown .fas Vl:consisting of two separateV parts, a lowerpart and an upper part 37'; but iitfis to be understood 'that separation `of `the'column into distinct parts in 'this manner -isnot .essential Yto therpractice ofjthe invenlt is 'however an especially advantage- A:ous .arrangementfand is flierein preferred. The `entire `colurrn :is 'heavily lagged with fheat .-insulatingmaterial las indicated con- Mentionallymt 38. Said lgas :passing from the condenser through' pipe 135 enters the upper necltiyingcohmlneSfZ. Returning now to ythe liquid condensate going 'to pump :23 through -;pipe\f22, thisV crude iirs't-stag'e compression condensategfis;elevated'bythe pump j23'tlrrough 'pipe 2:3zto alowerfse'cti'on oi the lower rectify- 'ing-ecolurmn l36. T-hecondensate impinges on a spreading .cone 39 yand flows downwardly 'overathe 'packing 40, rpaclringiof the `ring type nr jlackstone type `'beingespecially suitable. Each :of the sections containing vpacking as indicated may be entirely lilled therewith, but-or'simplic'ity :of illustration the various ipacked sections ofthe complete distilling columnare shown only conventionally. Instead fof paclredfsections, the bubbler-'cap and tray ltype 'of `construction may be aisecl. The crude .compression condensate fed to the lower sec- 4tion. of fthe lower distillin-g column 36 is brought into intimate contact with anas'cending vapor with the result that the downwardly iiowing liquid becomes richer in less volatile componentsand the ascending vapor richer in the 'more volatile components. In

@ther words, the voperation is a true rectitication or fractional distillation. The vapor entering the bottom of the lower -rectifying `col-umn iscthe vapor coming fromtheiheaters L'and 28;, through vapor linesil and' 42 respectively. Liquid flows from the bottom of r-the lower column through pipe 43to the heater 28, andy from there through .pipe 44 to the heater 1.5., from the vaporizer 15 to a cooler 45, and from the cooler to storage tanks (not shown). The liquid product passing successively through heaters 28 and 15 may be regarded as an intermediate product whose composition approximates more and more nearly, as'it progresses through the heaters, the composition of the desired final liquid product. A portion of this intermediate productis .vaporized in the heaters, supplying the vapor entering the lower part of the .column system through lines il and 4:2 above mentioned. VThe unvaporized portion led away from heater 15 through cooler Ll5 is the final productoi the operation. The crude second-stage compression condensate' from Vcondenser 32 fand heater 28V isV elevated by pump 30 through line 30 and discharged upon a distributing cone-46 in a higher -section of the rectrfymg column system, 1n 'this linstance the uppermost Ysection Vof the lower column 36. The liquid-from thejlower section of the' upper column alsoflows through a trap i7 upon' this same cone. The vapor leaving the top of the lower column passes to a partial or reflux condenser 48,3the condensate there formed returning through trap 49 and discharging upon aforesaid ycone 46 of the :lower column. The uncondensed portion of the vaporfrom )the lower 'column enters the lowerpart of 'the lupper :column throughpipe 49a. rlhe gas 'from'second-stage condenser 32 also enters the lowerpartof'the upper column ashereinbeore stated. Y

In the upper column the'ascending gasiand "vapor meet descending liquid-and the composition of both phases .changes in the usual sense. Heptane,hexane,pentane and'asmuch of the butane as desired may be' removed from the ascending gas and vaporby contacting it with an appropriate'descending liquid. Gas and'vapor leaving 'the top .of the upper column through vapor line 50'pass into a condenser 5l which in most instances is cooled by l artificial refrigeration and should be heavily lagged with heat insulating material. The liquid formed in this condenser consists principally of propane with `some bu-tane. This is the reflux liquid which, passing through trap 52', is discharged through ypipe 53 upon distributing cone 54 of the upper column and makesposs'ible thechanges 'in Vcomposition just mentioned. The gas, denuded of its valuable gasoline: hydrocarbons, passes through a pressure relief valve 55 where the r pressure is lowered to any desired extent. l

The cooling of condenser 5l may be accomplished entirely or in part by expanding .the vdry waste gases through a suitable .engine Vin such manner that they are obliged to do' work Lf to eiifect the cooling ot condenser 5l in. this Cil manner, it maybe cooled by anyA ofthe ordinary methods of artificial,refrigeration.4 Ordinarily the vpartial condenser 48 is water cooled with very careful control so that just the required; amount, of reflux liquid is formed to effect the desiredv rectification in the lower column. Theuse `o this partial "condenser is optional, but it is especially desirable to employ, when artificial refrigeration is used to cool condenser 5l, or when the condenser 5l, if cooled', by the expanded dry gases, would not be able to produce the full cooling effect desired. The advisability of using the ypartial condenser 48 thus depends somewhat upon the cost of cooling in condenser 5l. As a rule it is Ymore economical to do part of the cooling with water in the partial condenser 48 than to do all the'cooling` in condenser 51 if the latter has to be cooled by artificial refrigeration. p

By interposing a partial condenser between the upper andflower columns, as'v herein disclosed, a substantial load is thus taken off the condenser 51. Vere the vapor allowed to pass from the lower column directly into the base of the upper column, a thermally equivalent weight of liquid reiiux would have to be formed in condenser 5l. In said condenser 51,vapors and gases are mixed and it is more difficult to transfer heat from this Vapor-gas mixture than if the vapors alone were present, as is substantially the case in the interposed partial condenser 48. Furthermore condensation in'l occurs at a lower temperature. It is evident, therefore, that the use of partial condeiiser 48 lowers the lirst cost of the apparatus and reduces operating cost.V Y Y For the sake of simplicity the present schematic illustration of the apparatus omits :for the most partY any showing of valves in the piping connections, but it is to beA understood that such valves are employed wherever it is necessary to control iiow of vapor ,or liquid through the respective lines.

lVhile embodiments of the novel procedure land apparatus have been hereinabove de- 'ing components of such liquid product,

which comprises subjecting successive quantities of such a gaseous mixture to compression in a continuous operation, thereby obtaining a hot compressed gaseous mixture and a. liquid compression condensate, said compression condensate comprising components of the original gaseous mixture which are normally liquid together with undesirable volatile components, bringing said hot compressed gaseous mixture into heat-transferring relationwith an intermediate liquid product more nearly approximating in composition the desired inal liquid product than `does the kaforesaid compression condensate, whereby to volatilize 'a portion of said intermediate liquid product, countercurrently contacting the resultant hot vapors with the aforesaid compression condensate to reduce its content of relatively highly volatile components and to obtain said intermediate liquidproduct, and leading away the unvaporized portion yof said intermediate `product as a product of the process.

2. The process of obtaining a valuable liquid product from a gaseous mixture containing the desired components of such liquid .to vaporize a. portion of an intermediateV liquid product more nearly approximating in composition the desired iinal liquid product than does said compression condensate, counter-currently contacting the resultant hot -vapors with the'aforesaid compression condensate to reduce its content of relatively highly volatile components and to obtainsaid intermediate liquid product, and leading away the unvaporized portion of said intermediate product as a product of the process.

3. The process Voi producing a desired liquid hydrocarbon product from a gaseous hydrocarbon mixture. containing components of such product together with Aundesirably volatile hydrocarbons, which comprises subjecting successive quantities of such a gaseous hydrocarbon mixture to compression in a continuous operation, thereby obtaining a hot compressed gaseous mixture and a liquid compression. condensate, said compression .condensate comprising normally liquid hydroca-rbons together with undesirably volatile hydrocarbons, utilizing the developed heat of compressionv of the gaseous hydrocarbon mixture to vaporize a portion of an intermediate liquid hydrocarbon product more nearly approximating in composition the desired iinal liquid product than does said compression condensate, countercurrently contacting the resultant hot hydrocarbon vapors with said compression condensate to reduce its content of relatively highly volatile hydrocarbons and to obtain said intermediate liquid hydrocarbon produc-t, and leading away the unvaporized portion of said intermediate product as a product ofthe process.

/lfThe process of .producing :a liquid hydrocarbon product from a gaseous mixture,

containing hydrocarbons lthat are desired Iin Y said product and others that are more volatile but con'densibleV therewith, Which comprises compressing such gaseous mixture to obtain a-crude'condensate comprising the norinall'y liquid hydrocarbons of the original gaseous mixture, likewise compressing an Vother quantity of said original gaseous 'mixture and utilizing its 'heat of compression to :drive off 'undesirable volatile hydrocarbons comprising vapors from a. liquid resulting from the above mentioned condensation, Vcoun-tercur'rently contacting said vapors With other quantitiesof liquid resulting from such abovementioned"condensation before thus depriving the liquidof-its undesirable volatile hydrocarbons, lthen subjecting this latter contacted Vliquid =to 'the developed heat of compression of further quantities of such first mentioned Agaseous mixture to reduce the Icontent of undesirable Vvolatile lhydrocarbons of the liquid to produce vthedesired liquid product'. l

5. The lprocessas `claimed in claim 1, further characterized by the fact that vthe gaseous Imixture operated upon is natural gas.

"6. The process as claimed in claim V3, further characterizedby the fact that l'the gaseous mixture loperated 'upon is natural gas'.

7. The process claimed in claim 2 further characterized by'thefact that the compression of said gaseous mixtu-rejis accomplis'hed in successive stages of 'increasing pressure, and the resultant condensates are rectified with the aid of heat 'derived from the said compression-stages. Y

8. The Vprocess of obtaining a valuable liquid product from a gaseous mixture, containing constituents ranging in boiling point from relatively high to relatively low, which comprises Acompressing such a gaseous mixture and `thereby obtaining on the one hand a liquidconsisting largely ofthe higher boiling constituents, and on the other hand a residual gaseous mixture consisting largely of the lower boiling constituents but including some of the higher vboiling constituents, countercurrently contacting said liquid With vapors formed by bringing -a liquid substantially free of said low boiling constituents into heat transferring lrelation With another quantity of said compressed gaseous mixture, condensing a `portion of the vapors surviving such rectification at ordinary Water-cooling temperatures and reiiuxling-the condensate, and countercurrently contacting the uncondensed vapors and the aforesaid residuall gas mixture With a re- 'fiux liquid obtained Iby condensing With the aid of refrigeration relatively lou7 boiling 'constituents of said gaseous mixture, "and utilizing vany surviving liquid from 'this operation" in the counter-current contacting 'operation lirst mentioned.

9. The processfof 'obtaining'a valuable liqproduct from a gaseous rmixture containing components of Widely varying volatility which comprises compressingsuchgasecus mixture to obtain al liquid condensate including the normally liquid'componentsof the original gaseous mixture, rectify'ingsaid :condensate With the aid'of a reflux obtained -at kWater-'cooling temperatures, yand subjecting kthe -uncondensed vapors, vtogether With the residual gases from the compression of A'said gaseous Vmixture, to 'rectification With the aidofareflux 'obtained at atemperaturebelov'v Vthat obtainable y'by Water cooling.

10. The process of producing natural fgas gasoline which comprises lcompressing natural gas to obtain a condensate including the normally liquidc'omponents of the' original gas, rectifying the resultant condensate with the aid of a reiiu'xobtaine'd at vvate'rcooling temperatures, and rectifying the residual gases from the compression with 'the aid of a reflux obtained at a temperature be- 'low that obtainable by Water cooling.

11. The process of producing natural fga's gasoline Which comprises compressing 'natural gas to obtain therefrom liquid condensate containing the normally liquid vcom-ponents of the original gas rand residual 'gas still containing desired gasolinefconstituents, and separating such constituents from 'said Kresidual-gas by rectiicatio'n,` including countercurrent contacting With a liquid reflux consisting principally of hydrocarbons lower-boiling 'than the major por-'tion ofthe na'tural gas gasoline to be produced, for which ythe necessary heat is derived from the aforesaid compression of the gas.

12. The process* of producing natural gas gasoline which comprises compressing'natur'al gas-to obtain a liquid phase con'sistinglargely of crude gasoline and a residual gaseous phase containing the less easily fliquefiable constituents, rectifying the aforesaid liquid phase with the aid of the heat of compression of the gas, and recovering the vdesirable Vconstituents from the residual gaseous phasefby scrubbing said phase vv'itha volatile hydrocarbon fraction previouslyforined from the gas itself.

13. Apparatus for 'producing natural gas gasoline Which comprises a compressor, fa heater, means forconducting h ot compressed gases from said compressor intoheat-'t'ransfe'rferring relation to'liquid in said heater, a second-stage compressor receiving uncondensed gases from the first compressor, a second heater arranged to be heated by hot gases from the second-stage compressor, distilling column means, and means forintr'oducing liquid condensate from both 4compressors and residual- 'uncondensed gases 'into the" distilling-column means i v 14. Apparatus for producing natural gas gasoline Which comprises a compressor, a heater, means for conducting hot compressed gases from said compressor into heat-transerring relation to liquid in said heater, a second-stage compressor receiving uncondensed gases from the first compressor, a second heater arranged to be heated by hot gases v from the second-stage compressor, distilling column means, and means for introducing liquid condensate from both compressors and residual uncondensed gases into the' distilling column means, said distilling column means including a partial condenser interposed bet-Ween the locality at which the uncondensed residual gases are introduced thereinto and the locality at which said liquid condensate is introduced.

15. The process of producing natural gas gasoline which comprises compressing natural gas to obtain a condensate including the normally liquid components of the original gas, rectifying the resultant condensate with the aid of a reflux obtained at Water cooling temperatures, rectifying the residual gases from the compression with the aid of a reiiux obtained at a temperature below that obtainable by Water cooling, and utilizing liqueiable components removed from said residual gases as a reflux in the iirst mentioned rectification.

In testimony whereof We hereunto aiiix our signatures.

EUGENE H. LESLIE. EDWIN M. BAKER. 

